blurred-location

A JavaScript library to help manage variable location privacy through a "blurred location" model

This library provides the "blurred location" model for leaflet-blurred-location - a Leaflet-based interface for selecting a "blurred" or low-resolution location, to preserve privacy

https:/publiclab/leaflet-blurred-location

The goal of this library is to provide the fundamental methods to implement a blurred location model, as described here: publiclab/leaflet-blurred-location#205

Definition of "blurred location"

See https:/publiclab/leaflet-blurred-location#how-it-works for an in-depth description of how blurred location works.

Features

The following functions are provided.

BL.returnZoomByPrecision(precision)

This function returns a Leaflet-style zoom level from precision - a number of digits of precision

BL.returnZoomByPrecision('1')
# => 10

BL.truncateToPrecision(number, digits)

This basic function truncates the given number to a provided number of digits, preserving zeroes to the appropriate precision.

BL.truncateToPrecision(1.2345678 , 2)
# => 1.23

BL.getMinimumGridWidth(pixels)

This in-progress function will return the width of a grid square in the following format, for a web map of the given pixel width:

{
  precision: VALUE,
  degrees: VALUE
}

This is used to calculate a usefully sized grid for a given map display.

BL.getGridCoordinatesFromLatitude(latitude)

This function calculates the grid size from the precision of the latitude value (the maximum zoom where a marker would be visible). This function depends on the dimension of the map container. To calculate distance in pixels between 2 coordinates, one should use the function as decribed in the documentation of map used (for example Leaflet).

BL.gridWidthInPixels() (planned, for integration with Leaflet)

---

Examples

See these in action in our test suite, here:

https:/publiclab/blurred-location/blob/main/spec/javascripts/test_spec.js